Cover; ADVISORY BOARD; Advances inPhysical Organic Chemistry; Copyright Page; Contents; Editor's Preface; Contributors to Volume 44; Biographical Essay: A. Jerry Kresge; 1 Introduction; 2 Solvent deuterium isotope effects; 3 Brønsted coefficients; 4 Generation of reactive intermediates by laser flashphotolysis; Acknowledgments; References; Chapter 1 The low-barrier hydrogen bond in enzymic catalysis; 1 Introduction; 2 Properties of hydrogen bonds; 3 Role of low-barrier hydrogen bonds in enzymatic reactions; 4 Conclusion; References; Chapter 2 Stabilities and Reactivities of Carbocations

1 Introduction2 Stabilities of carbocations; 3 Reactivity of carbocations; Acknowledgments; References; Chapter 3 Secondary equilibrium isotope effects on acidity; 1 Scope; 2 Theory; 3 Methodology; 4 Secondary deuterium isotope effects on acidities in solution; 5 Heavy-atom isotope effects on acidities; 6 Secondary isotope effects on Lewis acid-Lewis base interactions; 7 Secondary isotope effects on gas-phase acidity and basicity; 8 Secondary isotope effects on conformational equilibrium; 9 Secondary isotope effects on tautomeric equilibria; 10 Secondary isotope effects on hydrogen bonding

11 Secondary isotope effects in chromatography12 Secondary isotope effects on molecular structure; 13 Origin of secondary isotope effects on acidity; Acknowledgments; References; Chapter 4 Molecular dynamics simulations and mechanism of organic reactions: non-TST behaviors; 1 Introduction; 2 Nonstatistical product distribution; 3 Avoided intermediate on IRC; 4 Non-IRC reaction pathway; 5 Path bifurcation; 6 Reaction time course and product and energy distributions; 7 Nonstatistical barrier recrossing; 8 QM/MM-MD; 9 Full quantum MD simulation in water; 10 Summary and outlook; Acknowledgments

1 Catalysis and reversibility2 Catalysis of decarboxylation; 3 Decarboxylation, internal return, and directionality; 4 Pre-association; 5 Catalyzing thiamin diphosphate catalysis; 6 12C/13C kinetic isotope effects and pre-association catalysis; 7 Implications of blocking reversion for enzyme catalysis; 8 OMP decarboxylase -- decarboxylation and protonation of orotidine monophosphate; 9 General trends in catalyzed decarboxylation; 10 Decarboxylation of aromatic carboxylic acids; 11 Decarboxylation of 3-ketoacids; 12 Conclusions; References; AUTHOR INDEX; Cumulative Index of Authors